Association of a high-protein and low-glycemic-index diet during pregnancy with offspring growth and obesity until the age of 18 years – a target trial emulation

Background Maternal pre-pregnancy BMI and excessive gestational weight gain (GWG) are associated with offspring obesity. Moreover, maternal dietary patterns, particularly protein intake and glycemic index, influence GWG and fetal development. This study aimed to investigate the association of a high-protein, low-glycemic-index (HPLGI) diet during pregnancy with offspring growth and obesity. Methods Using observational data from the Danish National Birth Cohort, a target trial emulation was conducted to investigate the association of an HPLGI diet during pregnancy on offspring growth up to 18 years of age. A cohort of 17,551 women who met the inclusion criteria were categorized into exposure groups based on their protein intake and glycemic index to emulate the groups in the APPROACH trial. Results Offspring outcomes were assessed at various ages and a linear mixed model was used including potential confounders. Offspring born to women following an HPLGI diet during pregnancy had 2.59 kg higher body weight and 0.72 kg/m ² higher BMI at 18 years compared to those from the moderate-protein, moderate-glycemic-index (MPMGI) group. Maternal characteristics varied between the exposure groups, with the HPLGI women exhibiting 1.67 kg higher pre-pregnancy weight and 0.49 kg/m ² BMI, with no differences in GWG. Conclusion Offspring born to women consuming an HPLGI diet during pregnancy had higher body weight and BMI at 18 years compared to offspring born to women on an MPMGI diet. These findings raise questions about the long-term implications of maternal dietary patterns on offspring health. Further research is needed to elucidate the mechanisms underlying these associations.